C ++使用delete []删除结构数组 [英] C++ Deleting array of structures with delete[]

问题描述

我在向cpp中的数组添加结构时遇到麻烦.我想出了这种方法，该方法在ints上很好用，但是当我想在结构上做同样的事情时，添加3个或更多后会报错.我对其进行了一点调试，似乎delete []导致了错误消息分段错误(内核已转储)".我不能使用向量或stl中的列表，所以不要建议这是一些代码:

I'm having trouble with adding structures to array in cpp. I've came up with this method which works great on ints but when i want to do the same thing on structures im getting error after adding 3 or more. I debugged it a little bit and it seems that delete[] is causing error message "Segmentation fault (core dumped)". I cant use vectors or list from stl so dont suggest that Here's some code:

struct sth
{
    unsigned int id;
    std::string name;
};

unsigned int id_counter = 0;
unsigned int counter_int = 0;
sth *array = new sth[0];

void print_array()
{
    for (int i = 0; i < counter_int; ++i)
    {
        std::cout << array[i].id << ' ' << array[i].name << " -- ";
    }
    std::cout << '\n';
}

void add_sth(sth value)
{
    sth *newArr = new sth[counter_int + 1];
    memcpy(newArr, array, counter_int * sizeof(sth));
    delete[] array;
    array = newArr;
    array[counter_int] = value;
    ++id_counter;
    ++counter_int;
}

int main(int argc, char const *argv[])
{
    sth e1 = {1, "abc1"};
    sth e2 = {2, "abc2"};
    add_sth(e1);
    add_sth(e2);
    add_sth(e2);

    print_array();
}

推荐答案

问题可能是试图使用memcpy复制 std :: string .

The problem is probably trying to copy an std::string with memcpy.

std :: string 不是POD(普通旧数据)对象，某些编译器和当然是静态代码分析器，例如SonarQube或Klocwork会提醒您你在做什么错了.

std::string is not a POD (Plain Old Data) object, and some compilers and certainly static code analyzers e.g. SonarQube or Klocwork will alert you that what you are doing is wrong.

要正确完成复制，您应该定义一个赋值运算符，然后逐一复制项目，或仅使用动态容器，例如 std :: vector

To accomplish a copy correctly you should define an assignment operator and copy the items one by one, or just use a dynamic container e.g. std::vector

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